With rapid growth of mobile communications and great progress of technology, the world will move towards a fully interconnected network society where anyone or anything can get information and share data anytime and anywhere. It is estimated that there will be 50 billion interconnected devices by 2020, of which only about 10 billion may be mobile phones and tablet computers. The rest are not machines communicating with human beings but machines communicating with one another. Therefore, how to design a system to better support the Internet of Everything is a subject needing an in-depth study.
In the standard of Long Term Evolution (LTE) of the Third Generation Partnership Project (3GPP), machine-to-machine communication is called machine type communication (MTC). MTC is a data communication service that does not require human participation. Deployment of large-scale MTC user equipments can be used in such fields as security, tracking, billing, measurement and consumer electronics, and specifically relates applications, including video monitoring, supply chain tracking, intelligent meter reading, and remote monitoring. MTC requires lower power consumption and supports lower data transmission rate and lower mobility. The current LTE system is mainly for man-to-man communication services. The key to achieving competitive advantages of scale and application prospects of MTC services is that the LTE network supports low-cost MTC devices.
In addition, some MTC user equipments need to be installed in the basement of a residential building or at a position within the protection of an insulating foil, a metal window, or a thick wall of a traditional building; MTC suffers from more serious and obvious penetration losses from air interfaces, compared to that of conventional equipment terminals (such as mobile phones and tablet computers) in LTE networks. 3GPP decides to study the project design and performance evaluation of MTC equipments with enhanced additional 20 dB coverage. It should be noted that MTC equipments located at poor network coverage areas have the following characteristics: extremely low data transmission rates, low latency requirements, and limited mobility. In view of the above characteristics of MTC, the LTE network can further optimize some signals and/or channels to better support MTC services.
Therefore, at the 3GPP RAN #64 plenary session held in June 2014, a new MTC work item with low complexity and enhanced coverage for Rel-13 was proposed (see non-patent literature: RP-140990 New work Item on Even Lower Complexity and Enhanced Coverage LTE UE for MTC, Ericsson, NSN). In the description of this work item, an LTE Rel-13 system needs to support uplink/downlink 1.4 MHz RF bandwidth for an MTC user equipment to operate at any system bandwidth (for example, 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz). The standardization of the work item will be completed at the end of 2015.
In addition, in order to better implement the Internet of Everything, another new work item was proposed at the 3GPP RAN #69 general meeting held in September 2015 (see Non-Patent Document: RP-151621 New Work Item: NarrowBand IoT (NB-IoT)), which we refer to as Narrowband Internet of Things (NB-IoT). In the description of this item, an NB-IoT user equipment (UE) will support uplink/downlink 180 kHz RF bandwidth. In the existing LTE system, a minimum granularity for resource allocation of the UE is one physical resource block (PRB). That is to say, resource allocation for a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) of the existing LTE system is based on a PRB. However, the NB-IoT UE supports uplink/downlink 180 kHz RF bandwidth only, i.e., RF bandwidth having the size of one PRB. A more accurate resource indication method having a smaller granularity is needed.